How to Make PDFs Accessible: A Complete Guide

What Is PDF Accessibility?

An accessible PDF is one that can be used effectively by people with disabilities — including people who are blind or have low vision (who use screen readers), people with motor impairments (who navigate without a mouse), and people with cognitive disabilities (who benefit from clear structure and reading order).

PDF accessibility is governed by two main standards:

• PDF/UA (ISO 14289) — The international standard for universally accessible PDFs
• WCAG 2.1 (Web Content Accessibility Guidelines) — The web standard, which many organisations apply to PDF documents as well

Many governments and large organisations are legally required to publish accessible PDFs under disability discrimination law (ADA in the USA, Equality Act in the UK, EN 301 549 in Europe).

The Six Pillars of PDF Accessibility

1. Document Tags

Tags provide a hidden structure layer that screen readers use to navigate the document:

• Heading tags (H1, H2, H3) — Navigable heading hierarchy
• Paragraph tags (P) — Body text blocks
• List tags (L, LI, LBody) — Bulleted and numbered lists
• Table tags (Table, TR, TD, TH) — Data tables with row and column headers
• Figure tags — Wrapped images

Without tags, a screen reader reads content in the order text objects appear in the PDF file, which often differs from visual reading order.

To add tags in Adobe Acrobat Pro:

1. Tools → Accessibility → Autotag Document
2. Review and correct the tag tree in the Tags panel

To verify tags exist: File → Properties → Description → check "Tagged PDF: Yes"

2. Reading Order

Even with tags, the reading order must match visual flow. Multi-column layouts and sidebars are common culprits where auto-tagging reads content out of sequence.

To fix in Acrobat Pro:

1. Tools → Accessibility → Reading Order
2. Numbered zones on the page show the current read order
3. Drag zones to reorder or reassign them

3. Alternative Text for Images

Every meaningful image needs alt text — a description a screen reader announces.

• Informative images: Describe what is shown: "Bar chart showing Q1 regional sales"
• Decorative images: Mark as Artifact so screen readers skip them
• Complex charts: Provide a full summary in the document body

To add alt text in Acrobat Pro:

1. Tools → Accessibility → Set Alternate Text
2. Click each image and type its description
3. Mark decorative images as "Decorative"

4. Meaningful Link Text

Links should describe their destination:

• Bad: "Click here" or a raw URL
• Good: "Download the 2024 Annual Report (PDF)"

Screen reader users often navigate by listing all links on a page — meaningful text lets them jump to the right link without reading surrounding text.

5. Colour Contrast

Text must have sufficient contrast against its background per WCAG:

• Normal text (under 18pt): minimum 4.5:1 contrast ratio
• Large text (18pt+ or bold 14pt+): minimum 3:1 ratio
• Never use colour as the only way to convey information

Free tool: WebAIM Contrast Checker at webaim.org/resources/contrastchecker

6. Accessible Forms

• Every form field must have a tooltip (the accessible label)
• Tab order must follow logical form completion sequence
• Required fields must be marked both visually and programmatically
• Error messages must identify which field has the error

In Acrobat Pro: select field → Properties → General → Tooltip

How to Check PDF Accessibility

Adobe Acrobat Pro:

1. Tools → Accessibility → Full Check
2. Select all rules and click Start Checking
3. The results panel shows passes, failures, and manual review items

PAC (PDF Accessibility Checker) — Free: More thorough than Acrobat's built-in checker. Download from pdfua.foundation.

Manual testing: Use a real screen reader — NVDA (free, Windows) or VoiceOver (free, Mac/iOS) — to navigate the entire document using only the keyboard.

Creating Accessible PDFs from the Source

From Microsoft Word:

1. Use Heading styles (not just large bold text)
2. Add alt text to images: right-click → Edit Alt Text
3. Mark header rows in tables: Table Design → Header Row
4. Export: File → Save As → PDF → Options → Document structure tags for accessibility

From InDesign:

• Use paragraph styles for all headings and body text
• Tag images using the Articles panel
• Export with Create Tagged PDF checked

Frequently Asked Questions

Does PDF/A guarantee accessibility? No. PDF/A and PDF/UA are separate standards. A PDF can be PDF/A compliant but inaccessible.

Can I make a scanned PDF accessible? Yes — run OCR first, then add tags and alt text. Scanned PDFs require significant additional work.

How long does it take? A simple one-page document: 15 minutes. A complex 50-page report: several hours. Starting from an accessible source document dramatically reduces remediation time.

Summary

Accessible PDFs need tags, correct reading order, image alt text, meaningful link text, adequate contrast, and properly labelled form fields. The easiest path is building accessibility into the source document (Word or InDesign) before exporting. Use Acrobat Pro's Full Check and the free PAC validator to verify, then test with a real screen reader — automated checks miss roughly 30% of issues.